Self-pumping heat exchange unit

ABSTRACT

In addition to efficiently removing residues from the inner wall of the inner tubes ( 20 ), reducing head loss and substantially improving the heat transfer coefficient, the present invention also allows obtaining different pumping flow rates for the product fluid. More particularly, the heat exchange unit ( 1 ) stands out because it comprises an elongated rotary rod ( 30 ) arranged inside at least one inner tube ( 20 ) and provided with cleaning means comprising scraping elements ( 40 ) suitable for scraping and detaching the product fluid accumulated on the inner wall of the at least one inner tube ( 20 ); and an endless spiral ( 50 ) dimensionally suitable for surrounding the rotary rod ( 30 ) longitudinally through the spaces existing between the scraping elements ( 40 ), said endless spiral ( 50 ) being suitable for displacement of the product fluid circulating through the at least one inner tube ( 20 ), generating a self-pumping effect.

OBJECT OF THE INVENTION

The present invention belongs to the field of heat exchange apparatuses, and more specifically to machines for heat exchange between fluids having the same or different characteristics, applicable in different sectors, such as the food sector, pharmaceutical sector, health sector, etc.

The main object of the present invention is a heat exchange unit which fundamentally stands out because it provides a self-pumping effect and keeps the exchange surface clean at all times, improving the heat transfer coefficient and allowing a substantial reduction in head losses through its inner and outer tubes.

BACKGROUND OF THE INVENTION

Machines for heat exchange between fluids which generally have at least one inner tube through which the “product fluid”, i.e., fluid to be heated or cooled, circulates and an outer tube or shell, through which the “service fluid”, i.e., heat transfer fluid, circulates are known today.

More specifically, heat exchangers the inner conduits of which are provided with cleaning means, thus providing a self-cleaning effect on their inner surface and allowing maintenance and a prolonged service life of said heat exchangers, reducing the dead time thereof, are known in the current state of the art. An example of the aforementioned exchangers can be found in Spanish patent application ES2158752. Nevertheless, current machines for heat exchange between fluids have several problems and drawbacks among which the following stand out:

-   -   They have a high head loss, which causes a considerable and         significant decrease in machine performance.     -   The inner walls of their tubes experience very high pumping         pressures with the risks and problems it entails, particularly         in cases of high viscosity fluids or fluids with a concentration         of solids.     -   They do not allow regulating or modifying the pumping flow rate         of the product fluid since it is predetermined by the pump         before the machines are connected thereto.     -   Their shells are single-pass shells, so they have a low heat         transfer coefficient, in addition to involving a greater demand         for pumping the service fluid to the pump, increasing costs.     -   The inner walls of the inner tubes are not completely cleaned,         the cleaning means not acting on parts or sections of said         tubes.     -   They must be connected to a pump which moves and pumps the         fluids circulating through the inside of the tubes.     -   The mechanisms for opening current exchange machines when         performing inspection and maintenance tasks are complex, slow         and tedious mechanisms.     -   They are only operative for a specific type of low viscosity or         high viscosity fluids, but without the possibility of working         with both fluids.

DESCRIPTION OF THE INVENTION

The present invention solves the aforementioned drawbacks by providing a self-pumping heat exchange unit which successfully reduces head loss through its conduits, substantially optimizing the heat transfer coefficient, and also allowing regulating and obtaining different pumping flow rates for the product fluid, i.e., fluid to be heated or cooled.

More particularly, the heat exchange unit object of the invention is of the type comprising an outer shell provided with an inlet and an outlet for a “service” fluid, i.e., a heat carrier fluid, being able to be glycol or cold water vapor, thermal oil, etc.; at least one hollow inner tube housed inside the outer shell and also linked to an inlet and an outlet for a product fluid, i.e., fluid to be heated or cooled; an elongated rotary rod arranged inside the at least one inner tube and having cleaning means for cleaning the inner wall of the at least one inner tube

Therefore, the heat exchange unit described herein stands out fundamentally because it additionally comprises: scraping elements linked to the rotary rod and suitable for scraping and detaching the product fluid accumulated or fixed on the inner wall of the at least one inner tube; and an endless spiral also linked to the rotary rod, dimensionally suitable for running along and surrounding the rod longitudinally through the spaces existing between the scraping elements, said endless spiral being suitable for displacement of the product fluid circulating through the at least one inner tube, generating a self-pumping effect.

The scraping elements preferably have an elongated planar configuration, thus allowing covering the entire the inner surface of the inner tubes, increasing cleaning efficiency.

According to a preferred embodiment, the heat exchange unit comprises three inner tubes. So by means of varying the rotational speed of the rods existing in the inner tubes, and therefore of the endless spiral, it is possible to achieve different pumping flow rates for the product fluid circulating through said inner tubes, which allows improving the heat transfer coefficient and reducing the head losses generated by friction of the actual inner walls of the tubes.

On the other hand, in relation to the drive of the rotational movement of each of the rotary rods, the arrangement of a geared motor connected through a central shaft with a main gear to which secondary gears connected with the ends of each of the rotary rods are linked, has been envisaged. Integral movement and synchronized rotation of the rods are thus achieved. The aforementioned main gear is also preferably made of stainless steel, whereas the secondary gears are manufactured from a plastic material, thus preventing the irritating noises produced by the transmissions of the gears, while at the same time said secondary gears are a fuse element as a means for protecting against surge currents.

Finally, it must be pointed out that the heat exchange unit herein described has been envisaged to be applicable in the food sector, health sector, environmental sector or industrial sector. It can be also used as a regenerative unit, i.e., using one and the same product fluid in both parts of the unit, namely, the shell and the inner tubes, thus recovering the actual energy of the product fluid.

Therefore, the present invention provides a heat exchange unit which, in addition to efficiently removing residues from the inner wall of the tubes, reducing head loss and substantially improving the heat transfer coefficient, also stands out for obtaining a “self-pumping effect” of the product fluid circulating through said inner tubes, which makes it possible for the requirements of the outer pump to be lower, even to the extent of being able to dispense with said outer pump in some cases, being a more efficient, economical and viable alternative solution than the self-cleaning systems of current heat exchangers.

DESCRIPTION OF THE DRAWINGS

To complement the description that is being made and for the purpose of aiding to better understand the features of the invention according to a preferred practical embodiment thereof, a set of drawings is attached as an integral part of said description in which the following has been depicted with an illustrative and non-limiting character:

FIG. 1 shows a general perspective view of the self-pumping heat exchange unit object of the invention.

FIG. 2 shows a perspective view of the shell of the exchange unit of the invention, with its inlets and outlets for the service fluid, three inner tubes being seen according to this embodiment.

FIG. 3 shows a perspective view of one of the rods arranged internally inside each of the three inner tubes of FIG. 2.

FIG. 4 shows a detailed view of the gears for driving each of the rods existing inside the inner tubes.

PREFERRED EMBODIMENT OF THE INVENTION

A preferred embodiment is described below with reference to the aforementioned drawings, without this limiting or reducing the scope of protection of the present invention.

FIG. 1 shows a general view of the self-pumping heat exchange unit (1) which comprises:

-   -   an outer shell (10), shown in greater detail in FIG. 2, provided         with an inlet (11) and an outlet (12) intended for the         circulation of a “service” fluid, i.e., a heat carrier fluid;     -   three hollow inner tubes (20) housed inside the outer shell (10)         and also linked to an inlet (21) and an outlet (22) for a         product fluid, i.e., fluid to be heated or cooled;     -   an elongated rotary rod (30), shown in FIG. 3, arranged inside         the at least one inner tube (20),     -   scraping elements (40) having an elongated planar configuration,         also depicted in FIG. 3, linked to the rotary rod (30) and         suitable for scraping and detaching the product fluid         accumulated or fixed on the inner wall of the at least one inner         tube (20), and     -   an endless spiral (50) also linked to the rotary rod (30),         dimensionally suitable for running along and surrounding the         rotary rod (30) longitudinally through the spaces existing         between the scraping elements (40), as seen in said FIG. 3, said         endless spiral (50) being suitable for displacement of the         product fluid circulating through the at least one inner tube         (20), generating a self-pumping effect.

Furthermore, as can be seen in FIG. 1, the heat exchange unit (1) additionally comprises a main geared motor (60) connected through a central shaft (70), shown in FIG. 4, with a main gear (71) made of stainless steel, the latter is in turn connected with secondary gears (72) which are linked to the ends of each of the rotary rods (30), as shown in FIG. 3. Said secondary gears (72), depicted in FIGS. 3 and 4, are manufactured from a plastic material, such that in addition to acting as a safety fuse element, it allows preventing the irritating noise generally produced by the transmissions of the gears.

Said FIG. 1 also shows an auxiliary geared motor (80) which is coupled to the main geared motor (60) and which allows separating the heat exchange unit into two blocks when connected with a threaded screw and a nut for a quick, simple and comfortable opening of the heat exchange unit (1), facilitating inspection and/or maintenance tasks by qualified personnel. Finally, it must be pointed out that the unit incorporates a lower frame (90), also shown in FIG. 1, making up the base support of the heat exchange unit (1), and which in the present embodiment further comprises an additional telescopic prolongation (91) provided with wheels (92) in the lower portion, thus facilitating its movement and allowing it to take up minimum space.

Finally, the improvements and advantages obtained by means of the heat exchange unit of the present invention must be mentioned:

-   -   A total performance increase as a result of a substantial         reduction in head loss through its conduits.     -   Problems derived from high pumping pressures are eliminated due         to its self-pumping effect.     -   Possibility of regulating the pumping flow rate of the product         fluid according to the needs of each application.     -   “Multipass” possibility of the endless spiral, thus improving         the heat transfer coefficient, so the requirements of the pump         are lower.     -   Maximizing cleaning of the inner walls of the inner tubes.     -   It allows dispensing with or significantly reducing the needs of         a preceding pump since the self-pumping effect is sufficient.     -   It allows quick, comfortable and simple opening/closing of the         exchange unit for inspection and/or maintenance tasks.     -   It allows working and operating with different types of low or         high viscosity fluids. 

1. Self-pumping heat exchange unit (1) comprising an outer shell (10) provided with an inlet (11) and an outlet (12) for a heat carrier fluid; at least one hollow inner tube (20) housed inside the outer shell (10) and also linked to an inlet (21) and an outlet (22) for a product fluid, that is, fluid to be heated or cooled; an elongated rotary rod (30) arranged inside the at least one inner tube (20) and having cleaning means for cleaning the inner wall of the at least one inner tube (20), the heat exchange unit (1) being characterized in that said cleaning means comprise: scraping elements (40) linked to the rotary rod (30) and suitable for scraping and detaching the product fluid accumulated or fixed on the inner wall of the at least one inner tube (20), and an endless spiral (50) also linked to the rotary rod (30), dimensionally suitable for running along and surrounding the rotary rod (30) longitudinally through the spaces existing between the scraping elements (40), said endless spiral (50) being suitable for displacement of the product fluid circulating through the at least one inner tube (20), generating a self-pumping effect.
 2. Self-pumping heat exchange unit (1) according to claim 1, characterized in that the scraping elements (40) have an elongated planar configuration.
 3. Self-pumping heat exchange unit (1) according to claim 1, characterized in that it additionally comprises a main geared motor (60) connected through a central shaft (70) with a main gear (71), in turn connected with the end of the rotary rod (30).
 4. Self-pumping heat exchange unit (1) according to claim 3, characterized in that the main gear (71) is made of stainless steel.
 5. Self-pumping heat exchange unit (1) according to claim 3, characterized in that it additionally comprises an auxiliary geared motor (80) which is coupled to the main geared motor (60) and which allows separating the heat exchange unit into two blocks when connected with a threaded screw and a nut.
 6. Self-pumping heat exchange unit (1) according to claim 1, characterized in that it additionally comprises a lower frame (90) making up the base support of the heat exchange unit (1).
 7. Self-pumping heat exchange unit (1) according to claim 6, characterized in that the lower frame (90) comprises an additional telescopic prolongation (91) provided with wheels (92) in the lower portion.
 8. Self-pumping heat exchange unit (1) according to claim 1, characterized in that it comprises three inner tubes (20).
 9. Self-pumping heat exchange unit (1) according to claim 8, characterized in that the main gear (71) is linked to secondary gears (72) connected with the ends of each of the rotary rods (30).
 10. Self-pumping heat exchange unit (1) according to claim 9, characterized in that the secondary gears (72) are made of a plastic material. 